He is leaner than I thought he'd be, and sparser-haired. Nevertheless it is him, Geoffrey Archer, ushering me into the front room of his house in well-to-do Kew, London. It is three hours before the verdict.

"Lord Archer," I begin.

"Oh," he says, disseminating a little frown. "Don't call me that." And shedding further pretensions, he repairs to the kitchen to make us some coffee.

I am left with Archer's publicist, Charlotte, who has set aside a pile of his books. All the favourites are there - Java Spider, Scorpion Trail, Skydancer - the thrilling intrigues of people in high public office. "Geoffrey Archer has every reason to consider himself first among equals," trumpets the Times across one dust jacket, cleverly incorporating another of his titles.

Sadly, discussion of his books must take a back seat today. There is only one topic in the Archer household. "Do you know if the verdict has come in yet?" whispers Charlotte, before the writer returns bearing refreshments. "How has your week been?" I ask him meekly.

The excellent joke here is that Geoffrey Archer is not Jeffrey Archer, despite writing thrillers, knowing a lot about politics, living in a posh part of London and having a son called James. The parallels are marvellous enough to make asking him the question "And how is the fragrant Mary?", seem paralytically funny. (In fact, his wife is called Eva, a teacher, and he answers questions of this nature with a tolerant but rather long suffering smile.)

He is 57, this Geoffrey Archer, four years younger than his namesake and studiously unpretentious. A precise and sober former defence correspondent for ITN, he's a good sport about his career-long association with a man he has come to call "the other Jeffrey". (I suppose if you have to be measured against someone else, Jeffrey Archer isn't a bad candidate: you will always come away from the comparison feeling thankful.)

"It's strange," says Geoffrey. "He's always been there in my life, a distant rumble in the background that occasionally got louder." The first rumblings occurred in 1964, when he was 20 years old. Geoffrey Archer was in his first job as a trainee television researcher in Southampton."When I started, one of the first things they to me said was, 'You must be that bloke who raised money for Oxfam and got on the news.'" But he wasn't. Geoffrey had never been on the news. That was Jeffrey, then at Oxford and in charge of a student fundraising event for which, despite its parochial nature, the young self-publi cist had succeeded in getting some national coverage.

At this time, Geoffrey and Jeffrey were quite similar in temperament: neither knew what to do with his life and each drifted through a series of false starts. After uninspiring exam results, Geoffrey skipped university and tried out as an actor, an engineer and a lawyer before becoming a journalist. After uninspiring exam results, Jeffrey falsified his papers and got into Oxford, before working briefly as a policeman and a PE teacher. "There was a youthful naivety about him," says Geoffrey, "and I think I had a bit of that as well."

Then, several months into his first job, Geoffrey Archer suffered a setback that the other Archer would come to know all too well: he was fired, for arrogance, after walking into his boss's office at the TV studio and giving him advice on how to run the company. "It was a lesson promptly learned," he says, ruefully. "A mistake never repeated." Jeffrey would not be so adaptable.

In the 1969 Louth by-election the future peer was standing for the Conservatives for the first time. "I had been a reporter at Anglia television, which covered that area, for several years," says Geoffrey. "So my name was known to the public. According to Michael Crick's biography, some of the local newspapers had described [the Tory candidate] as "television commentator, Jeffrey Archer". The theory is that some people voted for him thinking they were voting for me." At 29, the other Jeffrey entered parliament as one of Britain's youngest MPs, blissfully unaware of the few snatched votes he carried for an honest man.

So the other Archer's career took off. But Geoffrey Archer was no slouch. He worked his way up the television hierarchy to be a reporter on News at Ten, and by the early 1970s was famous enough to be receiving deranged fan letters. These provided a context for the first face-to-face meeting with his namesake.

"It was a strange incident," says Geoffrey, unnecessarily. "I call it the Mystery of the Missing Love Letters. I started get ting love letters from a lady in Essex. They were all rather odd and I suspect that mentally she wasn't quite there. She was very bad at getting the right address on the envelope, and sometimes it would just say Geoffrey Archer, London. Anyway, one day, the other Jeffrey came into ITN to be interviewed on the lunchtime news. As soon as he'd finished, he sent up a message to me in the newsroom, asking if I could come down and have a word with him. He presented me with a bundle of letters and said: 'These, I think, must be for you.'" They had been delivered to Jeffrey Archer at the House of Commons.

The encounter was too brief for Geoffrey to form any lasting opinions, although he says he found the other one jolly. Sadly, it would be their last meeting. The closest they would come again was spine to spine on the bookshelves of Britain, the most testing period of their semi-acquaintanceship.

Surely, I ask, in 1987, when Geoffrey had his first thriller published, he had reservations about inviting comparison with the other Jeffrey? (If he hadn't scrapped the novel he'd started in 1975, he might have forced just such an awkward consideration on his rival, who didn't publish his first novel, Not a Penny More, Not a Penny Less, until 1976.) But Skydancer, the unravelling of a missile crisis, would have to compete in cruel juxtaposition with the chart-topping back catalogue of the country's most successful thriller writer.

"It was an issue," says Geoffrey. "And I did wonder about using a pseudonym? But in the 1980s, I was pretty busy on television - it was a good decade to be defence correspondent, what with the Falklands War - so my face and name were quite well known to millions of people. It seemed madness not to use that."

Didn't the emergence of another Geoffrey Archer cause panic in the popular fiction- buying public? "I don't think there was any great confusion. I mean, if you look at the sales figures, when my first book came out it sold 2,500 copies in hardback. His books were selling hundreds of thousands of copies, streets ahead of mine in terms of sales. And it was the same in paperback. So there was no indication that people were buying my books thinking they were his." It is equally possible that readers ran screaming from his books thinking they were written by the other Jeffrey. "In the end," he says, gracefully, "I think each factor cancelled the other out."

Geoffrey Archer has only read one of the other Jeffrey's books, an early title called Shall we Tell the President. He vaguely remembers enjoying it. There is no record of whether the other Jeffrey has read Geoffrey, but now, with time on his hands, it might be a good time to start.